Process and apparatus for metallizing ores



July 7, 1925.

H. N. TRACY PROCESS AND APPARATUS FOR IETALLIZING om Fil ed Jan. 5. 1920 2 Shoots-Shut 1 hwy/77$! 66/0200 A! Tim],

July 7, 1925. 1,544,951 H. N. TRACY PROCESS AND. APPARATUS FOR METALLIZ ING ORES Filed Jan. 5. 1920 2 Sheets-Sheet 2 Patented July 7, 1925 i .t

H M -n new r L ANGELES, A FORN AS I GNQR am 12349:: reoqess. COMPANY, A T STEESHIP, HARMQN N- T AC GEORGE memms n, c. enmson. HABmEs L- A I Q AND WILLIAM A- MANSQNJTBIISTEES.

i we emsm M meeem ee e- Application filed a a 5, i939. Serial m 3433,5108

To qZZ whom it may con-0 7m:

136 known that I, 'HAR ON TRAQY, 2 citizen ot' the Unit-ed States, 1'es1d1n'g"at- Lo's Augeles, in the county of Los Angelesj ciili fo'fiiia, have invented new and" u s'efiil flh y movements in "Processes and 'App'ai aftus fer te'l z O s, f f which the euqvirig is specification. A r

ThisinVentiOn relates to such processes and apparatus as I have 'set 'ffo'rth inwn' Patent No". 1,214,844, cla ted ,Fe lii u aiy" 1917', Apparatus for reducing zi-nd' iietalli'zirig ote's; the present iiivention "r'eil atiii' g generally to such a process of inetalliz gdi' ektrat'ing the meta l'fr'orn tires in the g iei'al mannertherein set forth. This present applicziti qn' is also in part a eqntinuatioii (if my pi ibf"applieetiotifbr process anti elpparatus for rntilli zing ores, filed January 30 1919, under SeriarNo; 273,982; thi s pi esent aipplication taking the plaee ,Qfsid pi-1dr??- pli'eetie-n.

"The apparatus shown in Patent N 0. 1,214,841, is designed more pzirtiu'larly tibe ellectivetvitltores which ar house finely crushed that theyhaVe a great tendency'tp 016g OI; choke. The operhtioii in th'a'fi appmws' embodies the dwnward "pts's' age bf a cplumn of ore into and through all-shaped s'tfiji'et'ufe,"t'hrdugh which thehrepisses in a ore or "less c0ntinuoiisthrough themetalliz'ing liquid (iiiolte ileaifi in the U-shaped passage; 'lvitheertsiih'kiiids of Ores; and in br'cler to effect. a high" pif- Cent'a ge of extraction, 1 find it desi1il)le t9 cyusli the. r es very finely", end'then, inst ad of'feedi'ng the ores tl'imu'gh 'thea'pparatusiii a c0iiipaiatit ely solid; 61'' cpntilh 'uous iiiass, I find it desirable, in order to prevefntelpggiiig 6r ipassing 6r b'a1jling' i t the fires, to pass the tires threugh the 'ap'ptratus ielatively loosely, ihstead of inffleontinuous mass, so that the ores are at all times 100% and free from any ligi bility 't'p c'lgbr chbke, in the apparatus. The pfesfeht'i'nventibh is "distinguished by it process in' ivhic h theore is fea rlfi'ed meteor less loosely, as

specified, and further, pefc'ifi eilly, although net limited to this) theore 'i sb arfi e'd ever the sufface of the mdlten lead zind'isf m'oved (1'6Wn into the lead in intimate contact there- I "KP; u., (1'1 '.'s In,

e-si 9 rd .e e te yfie er u thi dized, a considerable quantity jfqt tvill he In the drawings I illustrate generally at 10 a pre-heater. or roaster in the form of a revolving drum; generally at 11 a de-oxidizer or reducer; and, generally at 12 a collector or amalgamator, being an apparatus for absorbing or amalgamating the reduced metal into a body of molten metalfsuch-as molten lead. For the purposes of the present invention, the preheater 10, and the reducer 11, have, as their functions, the initial heating of the ore and the reducing of the ore to reduce themetal therein to a metallic state; in which reduced heated state the ore is delivered to the collector 12. Broadly speaking, it will be seen that any ,form of preheater and of de-oxidizer (reducer) may be utilized; but in some cases it may not be necessary or desirable to use the three devices in combination. It may or may.not inany particular case be necessary to roast an ore before reducing or de-oxidizing it. And it is not an essential of the present invention, as considered in some of its aspects, that the ore be reduced and then immediately be passed into the collector. And it is possible to both heat and reduce the ore in the collector without previous action; or it is of course possible to put into the collector ore which has already been reduced in some independent manner, and this ore will then be heated in the collector and its metal extracted. And it is also possible to use a previously reduced ore and heat it in such a preheateras here shown, and then deliver the heated ore to the collector. In any such case, the non-oxidizing, or de-oxidizing atmosphere, may be introduced to the collector in any suitable manner and in any suitable form. However, the combination of a de-oxidizer or reducer with the collector apparatus is a convenient, economical and desirable one because the de-oxidizer then furnishes a non-oxidizing atmospherefor the collector, because one and the same provision of de-oxidizing or non-oxidizing atmosphere will serve both for the de-oxidizer or reducer and the collector. The deoxidizing gas used in the reducer may be passed also through the collector; or the spent gas from the de-oxidizer may be passed through the collector. Also one heating fire will serve for both the de-oxidizer and the collector. I find it economical and convenient to have a separate pre-heater for the ore, even if ore which has been independently reduced or de-oxidized is used, and if no de-oxidizer is used in the combination.

I illustrate an ore roasting or pre-heating drum at 15, of any suitable type and revoluble by any suitable mechanism. Ore is fed into this drum at its upper end through a chute 16 from a feeder bin 17. Heat is supplied by an oil or other burner at 18 which throws a flame through a chamber 19 into the lower end of the drum. The upper end of drum 15 communicates with a flue chamber 9 communicatin with stack 8, which provides means for exit of the gases of combustion and provides the desired draft. This draft should not 'be 'too large as otherwise the fine ore dust will be carried out the stack; and for this reason I vent the collector and de-oxidizer heating furnace independently of the drum.

The chamber 19 at'the lower end of drum 15 communicates with a downwardly extending pipe 20 which, at its lower end, communicates directly with reducing apparatus 11.

The reducing apparatus 111. show constructed in a form which is particularly adapted to handling such finely crushed ores as are adapted for the extraction of silver and lead, for instance, by this process. I employ a plurality of cylindrical chambers 21, each provided with a screW-conveyer 22. The lower end of vertical pipe 20 communicates with one end of the upper chamber 21; the spiral conveyer in that chamber conveys the ore toward the other end of the chamber where it then falls through a vertical connecting passage 23; and the conveyer 22 in the next chamber carries the ore through that chamber to the vertical. passage 24 through which the ore passes 1nto the collector apparatus 12. It will be understood of course that the chambers 21, with their screw conveyer 22, may be made as long as desired; that there may be as many such chambers arranged in series relation as may be desired; so that the time period of the ore in the de-oxidizing or reducing apparatus may be suitable for the ore being treated.

The collecting or amalgamating apparatus comprises essentially a liquid metal holding chamber 30, of a suitable length, and preferably somewhat oval in cross section with its longer section axis vertical. Through the upper part of this chamber there is a spiral screw conveyer 31 on a shaft 32. The chamber is kept filled with lead to a level preferably just over the top of shaft 32, the lead being introduced and withdrawn through a passage shown at 33. Shaft 32 is also provided with beater or muller arms 34 to carry the ore into the lead bath.

Below the spiral screw conveyor there is another longitudinal shaft 35 which carries on it a plurality of radial cleaner bars 36. These cleaner bars are arranged in such a manner. on shaft 35, so that, when the two shafts .32 and 35 are driven at equal speeds in opposite directions, (by gears37) the cleaner bars 36' will pass and scrape against the opposite faces of the spiral, as will be readily understood. These cleaner bars thus perform the oflice of the outer end of this conveyor through a" pipe or chute'42, which; in this case, preferably leads downwardly to a cooler 42*.

Cooler 42 may comprise a suitable shell with water tubes 42 arranged across it; The hot ore comes into contact with the tubes: steam is thereby generated which may be used for motive power. etc.- about the plant. At the same time, by this arrangement, air is excluded from= the ore until it has cooled.

The lead chamber is supported in a furnace chamber to-embodied i'n the-brickwork structure 44 whiclien'closes and forms the support for the various parts of the apparatus herein described: An oil or other"burner'4t7 furnishes" heat to the furnaee 45 to heat the collector apparatus 12 and to keep the' lead in proper molten condition and at a proper operating temperature. It is'pr'eferred to keep the lead at a temperaturehigh enough to keep it freely liquid; and yet of'course" not high enough to volatilize the lead, nor high enough to heat the ore'so' much as to cause it to have'an undue tendency to stick or ball.

The furnace chamber 45 communicates'at its rearend with thechamber 46 in which" theredueing apparatus 11 is mounted: and

from the upper endof' this chamber 46 there is a draft opening 43 which leads to any suitable stack, for carrying'off'the gases of combustion. Cha1nber'46' doesnot com municate with chamber 19: the gases of combustion from the'burner at 47 are not,

in this form of apparatus, passed throughthe preheating" drum 15: because in' this particularinstance' the preheating druin 15 is designed to be a roasting drum as well asa preheater and because excessive draft is not wanted in the drum;

The variousparts of the" apparatusmaybe driven from any suitable source; and

means may be provided in the driving arrangement for so regulating and controlling; or fixing for any particular ore; the relative speeds of operation; as will be hereinaft er described. Fon thepurposes 1 of illustration, although of course itwill be understood that my apparatus is not? limited The" various parts of" the a paratus driven by motors M- and eontmlied by ebstats? R. Thus the feedenat B which feeds the ore into the roasting" drum, and the roasting drum, may be controlled in speed, and also thespirals 22' in the reducing apparatus it may be controlledin speed and the spiral conveyor and other parts in the collector may be controlled in speed; and also the final discharge spiral conveyor 40 may be controlled in speed.

Of course'it will be readily understood that the apparatus herein shown may be'varied in size and an'angement; and the parts may be assembled in any desired degree of duplication in one plant, all as may be desired for any particular installation or for the treatment of anypartic'ula'r kind of ore, all as w'illbe readily understood bythose skilled in'the art.

In the'operation of myapparatus as now described, and preferably, I introduce the reducing fluid; preferably in the form of a gas, through the pipe 50 at the outer end of discharge conveyor 41. The reducing gas is either forced by its pressure or drawn by the draft throughthe apparatus, through theconveyor'pipe tl', and thence'into the collector andthence through the collector 12' and through passage 24 into the re- (lacing apparatus. It passes through the reducing apparatus and thence'thmu'gh the pipe 20into thechamber 19, where any gases (such'as CO) coniingun'used from the reducing appa'na tus are burned and become a part of the fuel; and thence through the drum 15' and into and through the discharge stackS. Now the operation of the various parts is preferably so regulated that the roasted and heated ore discharged fromthe drum 15 and discharged through the pipe 20 into the reducing apparatus 11, is not sufficient to clog thereducing apparatus 11. That is; the cylindrical chambers 21 of the reducing apparatus are preferably never completely filed with the ore; but the ore is fed throughthe cylindrical chamber-smote orle ss loosely bythe spiral conveyors'therein; so'that there is'at all timessuflicient space for fre'e pass'age of the reducing and of the spent gas "resulting from the reducing gas after'it has acted upon theores'in'the reducer. The ore droppingt'hrough connections 23 and 24-siftsdown through a'rediieing atmosphere. The ore passing from the reducing apparatus'lk passes directly down through the passage; 24 intothe collector and rests upon the" surface of the liquid lead. Now the parts are preferably rotated at such speed that the ore preferably terms only a relatively thin layer over the surface of theliquid lead; the ore being fed for war-(11y; at'a'll' times bythe conveyor 31, so that the oreris spread in auniform layer tin this particular provision; 'I Show the over the sweat of the lead; It willbe seen that the devices at lO1l form, in effect, a feeder for the collector apparatus. At the discharge end of the collector chamber the ore may be piled up somewhat to perhaps a little higher level than it is throughout the length of the collector chamber; and the discharge conveyor 40 takes the ore out of the collector chamber as fast as it is moved to the discharge end of that chamber.

Now, in the mode of procedure as hereinabove outlined, it will be seen that the ore, at all times when it is in the collector apparatus, is in a non-oxidizing atmosphere; in fact. in an atmosphere of the reducing or de-oxidizing gas. This reducing or deoxidizing gas first passes through the collector apparatus, then passes into the deoxidizing apparatus where it de-oxidizes the fresh unreduced and heated ore coming into the de-oxidizing apparatus from the preheater 10. The spent gas then passes on out through the pre-heater. However, it is pos sible, and particularly so with some kinds of ores which need not be so finely crushed, or with ores which do not have any great tendency to clog, to feed the de-oxidizing gas into the de-oxidizer at such a point as designated 50*. In all cases it will of course be understood that the de-oxidizing gas is fed in under a pressure sufiicient to exclude atmosphere from all the parts. If a suflicient quantity of ore is fed into the deoxidizing apparatus, so as to more or less partially fill the chambers 21; or if the screw conveyor in the upper chamber 21 is, for instance, run a little more slowly than the screw-conveyor in the lower chamber 21 so that the upper chamber .is somewhat more filled with ore than the lower chamber; then when the de-oxidizing gas is fed in at 50 under a sufficient pressure, a part of it would of course pass upwardly and a part pass downwardly. This gas, or at least a part of it, is used up in de-oxidizing the ore: so that the gas which then passes downwardly along with the ore into the collector is in that case, or partially is, the spent gas from the de-oxidizing operation. In this case it will be seen that the ore in the collector is in an atmosphere of spent gas from the dc-oxidizer, which spent gas is of course a non-oxidizing gas, under the conditions in the collector. The temperature in the reducer is usually higher than in the collector, to maintain an eflicient reducing temperature; and I protect the collector with a brick arch at 415*, so that it does not get the full heat of furnace 45. Arch 45 I now make of loosely laid brick; it is not completely tight. The collector 12 is heated mainly by radiation from the heated brick of the furnace. At the rear end of the furnace the gases are led through flues 45* into the chamber 46 above the arch and above the collector; and in this chamber 46 the reducer 11 is directly exposed to the heat of the gases of combustion.

In practice, the reducing gas is, in any case, fed to the apparatus somewhat in ex cess over that required for actual theoretical operation of reduction, so as to be sure of supplying the various parts of the apparatus, and particularly the collector apparatus, with a sufficient quantity of non-oxidizing atmosphere; and at a pressure sutficient to exclude atmospheric air from the whole interior of the apparatus.

I have said that one of the functions of the apparatus at F, 15, 11 is as a feeder for the collector apparatus 12. This apparatus is so regulated as to feed the ore to the apparatus 12 at a speed so that the apparatus 12 can keep the ore spread out over the surface of the lead in a relatively thin layer. The ore thus is maintained at all times in a comparatively thin layer floating above the lead. The buoyancy of this ore-the resistance which is opposed to sink the ore in the leadprevents the ore from being merely carried around with the conveyor. Thus the ore must be moved forwardly over the surface of the lead at all times by the action of the conveyor. There is thus no tendency to choking of the ore, the ore is at no time under any great pressure and is always loose and free; but at the same time the lead surface provides the necessary element to cause the ore to be moved longitudinally by the rotation of the conveyor screw.

The radial beater or muller rods at 34 provide means for carrying the ore into intimate contact with the lead. Their function is to agitate the layer of ore so that every particle of ore will be brought into contact with the liquid metal surface; and they of course to a certain extent carry the ore somewhat below the liquid metal sur face. I preferably keep the molten lead level just slightly over the top of shaft 32, so as to prevent the ore from coming into direct contact with the shaft, and thus prevent any tendency of the ore to stick to the shaft. The whole apparatus is to be so designed and the conditions of operation are to be so maintained, to suit any particular kind of ore, that the ore is carried through the apparatus in as large quantity as possible, and that each particle of ore is carried into intimate contact with the liquid lead. Under these conditions the ore which emerges from the final discharge pipe at 42 is entirely spent; or practically entirely so. I have found by actual operation of an apparatus of the kind herein described, carrying on my process as herein described, that I am enabled to obtain extractions better than ninety percent from lead and silver ores, for instance.

The spirals and the beater fingers slip through the ore comparatively easily and do notexert any great pressureagainst it; although-the spirals have a tendency at times to .pick up a piece of ore; and if this piece of ore were left upon the spiral it would of course immediately form the nucleus for gathering other particles of ore and the spiral would soon become balled up. The cleaner fingers on the shaft 35 effectually prevent this. The spiral does not have to exert any great longitudinal pressure against the ore to move it; and the beater fingers disturb the ore slightly each time they pass through the layer of ore. There may be a large number of these beater fingers.

The spent ore at times carries with it small particles of the lead; but these may be recovered easily by cooling the gangue below the melting point of lead (in the cooler 42*) and then separating the lead out by any suitable mechanical methods. A dry concentrator will do this effectively. The values are taken out of the apparatus by withdrawing a part of the lead bath from time to time. In fact, from time to time a part of the lead bath may be withdrawn and new lead put into the bath.

By my process of operation the ore is'kept free flowing and capable of coming into intimate contact with the liquid metal and giving up its metal. And at the same time I provide means for effectually moving the ore and for saving the lead from loss by oxidization; and also for preventing any reratus in the manner here described, and the temperature in the apparatus may then be raised to such a point as to heat the ore sufficiently to then cause the reducing action on the ore; and then the collection operation, as hereinbefore described, will take place. In such a case the collecting or amalgamating apparatus, becomes, in itself. an apparatus complete in itself for reducing, metallizing and collecting the metal from the ore. It is not a requisite of my invention. in its broader aspect, that a preheating or reducing apparatus must be used with the collecting or amalgamating apparatus, as separate elements of the operation.

Having described a preferred form of my invention, I claim:

1. A method of extracting metal from ores containing metal in metallic state, embodying passing the ore over the surface of a liquid metal, and moving the ore into int-imate contact with the liquid metal as it passes over it.

2. A method of extracting metal from ores containing metal in metallic state, embodying passing the ore over the surface'of a liquid metal, moving the ore into intimate contact with the liquid metal as it passes over it, and maintaining a non-oxidizingatmosphere on the ore and liquid metal.

A method of extracting metal from ores containing metal in metallic state,embodying passing the ore over the surface of a liquid metal in a relatively thin body.

4. A method of extracting anetal from ores containing metal in'metallic state, 'embodying passing the ore over the surface of a. liquid metal in a relatively thin body, and moving the ore into intimate contact with the liquid metal asitipasses over-it.

5. A method of extracting metal from ores containing metal in metallic state,-embodying passing the ore over the surface of a liquid metal in a relatively thin body, moving the ore into intimate contact with the liquid metal as it passes over it, and maintaining a non-oxidizing atmosphere on the ore and liquid metal.

6. A method of extracting metal from ores containing metal in metallic state, em-

bodying passing the ores into contact with heated molten metal, and maintaining upon the ores and upon the heated molten metal throughout the period of contact between them a non-oxidizing atmosphere.

7, A process, embodying reducing metallic ores, passing the reduced ores into contact with liquid metal to extract the reduced metal, and maintaining a non-oxidizing atmosphere on the ores,'-throughout the operations of reduction and extraction.

8. A process, embodying continuously reducing metallic ores, continuously passing the reduced ores into contact with liquid metal to extract the reduced metal, and continuously maintaining a non-oxidizing atmosphere on the ores throughout the operations of reduction and extraction.

9. A process, embodying continuously reducing metallic ores, continuously passing the reduced ores into contact with molten metal to extract the reduced metal, and continuously maintaining a non-oxidizing atmosphere on the ores and on the entire body of molten metal during the operations of reduction and extraction.

10. A process, embodying reducing metallic ores in a reducing atmosphere, pass ing the reduced ores into contact with the upper surface of a body of liquid metal and maintaining a non-oxidizing atmosphere upon the ores throughout the period of contact with the metal. v

11. A process, embodying reducing metallic ores in a reducing atmosphere, passin the reduced ores over the surface of a liqui metal and maintaining a non-oxidizing atmosphere upon the ore and upon the liquid metal.

12. A process, embodying reducing metallic ores in a reducing atmosphere, passing the reduced ores over the surface of a body of liquid lead, and maintaining a nonoxidizing atmosphere upon the ores and upon the liquid lead.

13. A process, embodying reducing metallic ores, passing the reduced ores immediately across a body of liquid metal, and maintaining a non-oxidizing atmosphere upon the ores throughout such operations and upon the liquid metal.

14. A process, embodying reducing metallic ores, passing the reduced ores immediately across a body of heated molten metal, effecting intimate contact between the ore and metal, and maintaining a nonoxidizing atmosphere upon the ores throughout such operations and upon the heated molten metal.

15. A process, embodying reducing metallic ores in a reducing atmosphere, then passing the reduced ores over the surface of'a liquid metal, and maintaining a nonoxidizing atmosphere throughout the contact area of the metal.

16. A process, embodying reducing metallic ores in a reducing atmosphere, and then passing the reduced ores over the surface of a liquid metal, and maintaining thereon an atmosphere of the spent reducing atmosphere used to reduce the ores.

17. A process, embodying reducing metallic ores in a reducing atmosphere, and then passing the reduced ores over the surface of a liquid metal, and supplying a surplus of such reducing atmosphere at a pressure to exclude atmospheric air and maintaining an atmosphere over the liquid metal of the surplus and of the spent parts of the reducing atmosphere used to reduce the ores.

18. Apparatus of the character herein described, embodying a liquid metal holding chamber adapted to hold a charge of liquid metal partially filling it, a conveyor adapted to move ore into contact with said liquid metal, means to supply ore to the conveyor, and means to maintain a non-oxidizing atmosphere in the chamber.

19. Apparatus of the character herein described, embodying an element in which an ore is reduced, an element in which metallic metal is extracted from such reduced ore, means for discharging reduced ore from the first mentioned element into the second mentioned element; and means for feeding a reducing gas into both elements in common, so as to form a continuous atmosphere of reducing gas for the ore throughout both elements.

20. Apparatus of the character herein described, embodying an element in which an ore is reduced, an element in which metallic metal is extracted from such reduced ore, means for discharging reduced ore from the first mentioned element into the second mentioned element; said elements being in communication with each other so that they may have a common atmosphere; and means for feeding a non-oxidizing gas into the elements to provide a non-oxidizing atmosphere throughout both of them.

21. Apparatus of the character herein described, embodying a liquid metal holding chamber adapted to hold a charge of liquid metal partially filling it, a conveyor adapted to move ore over the surface of said liquid metal, means to supply ore to the chamber, and means to maintain a non-oxidizing atmosphere in the chamber.

Apparatus of the character herein described, embodying a liquid metal holding chamber adapted to hold a charge of liquid metal partially filling it, a conveyor adapted to move ore over the surface of said liquid metal, means to supply ore to the chamber, regulatable so as to maintain at all times a thin layer of ore over the surface of the liquid metal, and means to maintain a nonoxidizing atmosphere in the chamber.

23. Apparatus of the character herein described, embodying a liquid metal holding chamber adapted to hold a charge of liquid metal partially filling it, a conveyor adapted to move ore over the surface of said liquid metal means to supply ore to the chamber regulatable so as to maintain at all times a thin layer of ore over the surface of the liquid metal, means to maintain a non-oxidizing atmosphere in the chamber, and means in conjunction with the conveyor to beat the ore into the liquid metal during its movement over it.

24. Apparatus of the character herein described embodying a liquid metal holding chamber adapted to hold a charge of liquid metal partially filling it, a screw conveyor extending longitudinally of the chamber and horizontally therein, and adapted to move ore over the surface of said liquid metal, means to supply ore to the conveyor, and means in co-operation with the conveyor to disturb the ore and to cause it to be carried into intimate cantact with the liqiud metal.

25. Apparatus of the character herein described, embodying a liquid metal holding chamber adapted to hold a charge of liquid metal partially filling it, a screw conveyor extending longitudinally of the chamber and horizontally therein, and adapted to move ore over the surface of said liquid metal, means to supply ore to the conveyor, and means in co-operation with the conveyor to disturb the ore and to cause it to be carried lit) into intimate contact With the liquid metal,

said means embodying radial beater fingers mounted upon the screw conveyor.

26. Apparatus of the character herein described, embodying a horizontal liquid metal chamber adapted to hold a charge of liquid lnetal partially filling it, a horizontally extending conveyor adapted to move ore over the surface of said liquid metal, means to supply ore to the conveyor, and cleaner means in said chamber adjacent said conveyor and operatable with said conveyor to clean from it any ore which may adhere to the conveyor.

27. Apparatus of the character herein described, embodying a horizontal liquid metal chamber adapted to hold a charge of liquid metal partially filling it, a horizontally extending conveyor adapted to move ore over the surface of said liquid metal, means to supply ore to the conveyor, and cleaner means in said chamber adjacent said conveyor and operatable With said conveyor to clean from it any ore which may adhere to the conveyor, said cleaner means embodying a shaft parallel to the conveyor and close to it, and a plurality of cleaner bars mounted upon said shaft, and adapted to rotate into contact with the spiral conveyor.

28. A process of extracting metal from ores containing metal in metallic state, embodying passing the ores in comparatively small mass into intimate contact With a metal, which is maintained in molten and oxidizable condition by heat, and maintaining a non-oxidizing atmosphere upon the entire body of ores and upon the liquid metal.

29. A process of extracting metal from ores containing metal in metallic state, embodying introducing the ores together With a non-oxidizing atmosphere into intimate contact with a metal which is maintained in molten and oxidizable condition by heat, and maintaining the non-oxidizing atmosphere on the surface of the liquid metal.

In witness that I claim the foregoing I have hereunto subscribed my name this 29th day of December, 1919.

HARMON N. TRACY.

WVitness VIRGINIA BERINGER. 

